Lens calibration yes or no

Lens calibration yes or no ?
As you probably have read in last weeks posts about the ColorMunki and the FAQ about calibrations I’m a huge supporter of calibration. Today a topic some people don’t think about, or maybe not even know about, the lens….. calibration.

Now some people will claim that this is a minor thing, and don’t get me wrong they will get great images (or at least it could be that they get great images) but when you want to deliver continuity and use actions for certain looks in Photoshop/Lightroom (etc) and want that all your images look the same you will have to take some steps in your workflow.

It all starts with the colorchecker.
I’m using the Colorchecker Passport from X-rite, just shoot it as the first image in a session and you will have a perfect starting point to build from. Creating the profile is “easy peasy”, just use the fully automated plugin in Lightroom or if that doesn’t work use the desktop software. The only “problem” with the profiles the colorchecker passport creates is that they are only usable in software that supports DCP profiles (Lightroom and Photoshop), but don’t be too sad… in Capture one or aperture you can still use the graypatches for removing colorcasts and at least have a good starting point. In my opinion this is the least you can do, well ok, a whitebalance card is actually the least you can do, but seeing the pricing of the colorchecker passport I think it’s a no-brainer.


The next step that you really should do is calibrating the monitor, you can buy a “cheap” filterbased meter or an accurate spectrometer like the ColorMunki (see the review from last week). If you print yourself, at least use the right profiles with the right paper, the printer manufacturer often supplies this. Or if you want to do it really right, especially handy when you use non standard ink or an older printer, or are (like me) just very picky about quality, use the ColorMunki again, it can build a custom profile for your printer/paper/ink combination. Now that we have all this in order we can take it up a notch.


Calibrating the lightmeter.
I’ve written many articles on this and you can find them by selecting the menu option on the right called “lightmeter”.
But the quickest way (if you own a Sekonic meter that supports their software) is to use your colorchecker passport (or other compatible card) and use the supplied Sekonic software.
If you don’t own a meter that supports their software you can always use an 18% graycard and make sure the spike in the histogram reads app 128.128.128, remember this is IN your retouch software, IN the color space you use AND with the curves you use in your RAW workflow. There is a lot of debate about whether it should read 128.128.128 or something else so during the Photokina I decided to ask it to someone who really knows everything about this kind of stuff and he confirmed that the method works as long as you use it in the matter I say, he actually claimed it was app but that’s nitpicking 😀


So now we have a fully calibrated workflow…. Meaning if we meter the scene, take the shot it will show up correctly on our monitor (when we attach the profile from the colorchecker) and when we print it will also look as close to the original as possible (monitor and print are always a bit different).


So now we’re done right?
Well sorry actually no……
Did you ever (like me) read a lens review were a certain lens was destroyed by the reviewer due to softness and the competing lens was much sharper, while in your opinion you get great results?


Well that happens to me all the time, and I think in most cases it’s due to the fault of the reviewer, and trust me I’m not talking about the labs or the well known testing sites (I guess they will do what I’m telling you now). What a lot of people don’t seem to realize is that the combination of lens and camera are not always a perfect match, far from that. Maybe you heard the terms like back focusing and front focusing on some occasions? What this means is that when you focus on someone’s eyes it could be that the nose is in focus and the eyes are not. Now imaging this happening in a review but not that bad. I’ve seen some reviews where the reviewer was bashing a lens while I thought that his examples were actually not that far apart, the only difference was that brand A was pin sharp on the eye ball and brand B was pin sharp on the eye lashes. When you’re sure you focused on the eye ball you will select brand B as the clear winner of course…. Well that might be a big mistake.


In modern cameras there’s often a setting called “microadjustments”, what this does is it let’s you “calibrate” your camera/lens combination so that the focus “hits” the spot you want. Some cameras will allow you to do this for the general setting only but cameras like for example the Canon 5DMKIII will let you do it for the Wide end and Tele end of your lens. With the more advanced cameras, it will remember the lens but also if you use convertors or if you use a lens with a different serial number.


How it works
It actually couldn’t be more simple.
The first method is a simple do it your self but it’s rough.
Take three bottles put them in a row and focus on the middle one and see what your focus does… well that actually is not so good.
Better is to use a ruler and place this under an angle, like a 45 degree angle. Now focus on the middle of ruler and make sure that the camera and the focus point is as level as possible now check the focus in your camera or tethering software and you can exactly see where the focus falls, now that you have this information you can start adjusting the microadjustments and make sure that the focus is exactly on the point you focus on.


If you want to do it a bit more “professional” I can really advise the Spyder lenscalibrator, which I use myself and trust me it has solved many problems for my students who were complaining about their focus and did not even know they had the micro adjustment options in their camera.
The only thing you really have to take in mind is to shoot from a tripod, preferable remote triggering the camera (mirror lockup if you want to be really precise) and make sure that the camera your focus point is as level as possible, and shoot wide open.


The whole process will take you app under 5 minutes per lens, so imaging having all your lenses calibrated within 20 minutes and nail focus everytime…. And when you don’t you know it’s not your fault.
Remember that remark about the review?
Recently I bought a Tamron 24-70 f2.8 VC and seeing some reviews from this lens I saw a huge difference from people claiming it was pin sharp to people claiming it was too soft so they sold it. The first thing I did was take some test shots of course and I have to be honest… I was not blown away, but that was not due to the lens but the focusing, and when I threw in the lens calibrator it became clear why. On my 5DMKIII I need app -15 on the wide end and +18 on the tele end, seeing that 20 is the maximum this is pretty much. But after the calibration I became very happy with the lens because it’s really very nice and pinsharp after calibration.


Now when I compare this to my 70-200 f2.8 IS L (canon) which only needs a +2 and -3 calibration you can image what my review would look like when I would have compared both lenses without doing the calibration 😀


So when you are serious about your images, and without any doubt when you shoot a lot of shallow depth of field stuff make sure you check if your camera has the micro adjustment option and invest in a ruler (three bottles) or the spyder lens calibration tool and check your lenses. And if you don’t have that option make sure you do the test anyway because it might become clear to you that it’s not you but the lens/camera that makes your images not as expected.
Most camera repair centers will calibrate your lens/camera combination (at a fee) if you don’t have the micro adjustments in your camera, however if you own a lot of glass it COULD be wise to upgrade to a camera with this option, but you have to decide this for your self.
Now to make it more “fun” why not share your results here, just tell us if your lenses were “off” and if you could correct it.


Good luck…
Oh and please don’t blame me if you start seeing things that normally never bothered you 😀